Tampa Bay Watershed Climate

The climate of the Tampa Bay watershed is humid subtropical. The temperatures are modified by winds that sweep across the peninsula from the Gulf of Mexico. The mean annual temperature is 72.2 degrees Fahrenheit. The long summers are warm and humid, but thunderstorms occur almost every afternoon and prevent temperatures from becoming extremely high. Daytime temperatures during June, July, August, and September average near 90 degrees Fahrenheit.

Winters are short and mild; many of the days are bright and sunny, and little rain falls. Cold spells, accompanied by cold winds, can be expected only a few times during the year, and they last only a few days. January is the coldest month with an average temperature of 60.8 degrees. The nighttime average temperature in January is 51.3 degrees, and the daytime average is 70.2 degrees. Freezes can occur once or twice in a season although many winters have no damaging freezes. The lowest recorded temperature in Tampa was 18 degrees (December 1962).

The average annual precipitation is about 50 inches. Generally, the rainy season begins in June and continues into September or October. During this period, the rainfall comes mainly in the form of heavy thunderstorms that can last for 1 or 2 hours. About 60 percent (29 inches) of the annual rainfall occurs during June through September. The remaining 20 inches of rainfall if spread fairly evenly over the other months.

The wettest year on record was 1959, when 76.57 inches of rainfall was recorded. The driest year recorded was 1956 with 28.29 inches of rain. The heaviest rain in a 24 hour period, 12.11 inches, was recorded in July 1960 at Tampa International Airport.

Moderately high winds and accompanying thunderstorms occur at all seasons of the year. From August through November, occasional disturbances of varying intensity, some of hurricane force, move northward from the tropics across the county. The heavy rains that accompany these storms are generally more damaging that the wind.